1. Field of the Invention (Technical Field)
The present invention relates to a scanning magnetic microscope based on optically detected magnetic resonance and embodiments thereof.
2. Description of Related Art
Significant progress in recent years in scanning tunneling microscopy (STM) and atomic force microscopy (AFM) have had a revolutionary impact in the direct imaging of atomic scale structure. Usually, STM and AFM devices are used for imaging of surface structures and cannot provide information about three-dimensional structures which are of the greatest interest in nano-technology, structural biology, bio-chemistry, and related fields of science. Magnetic resonance force microscopy (MRFM) was designed to meet the demands for imaging technology to be (1) nondestructive, (2) three-dimensional, (3) Angstrom-scale spatial resolution, and (4) capable of imaging individual biological molecules in situ. The recently developed techniques that demonstrate the highest sensitivity and spatial resolution are MRFM and optically detected magnetic resonance (ODMR). Significant progress in MRFM has been made since the first experiment, which was performed at IBM by a team led by Rugar. Today MRFM promises to achieve single spin sensitivity with several nanometer spatial resolution.
The main achievements in MRFM method are related to transfer of the detection of a very weak microwave signal to the detection of the mechanical oscillation of a micro-cantilever. Another option to enhance the sensitivity is transfer of the microwave signal to the optical domain which is realized in the ODMR method. Related single spin experiments were independently performed in 1993 by two groups led by Moerner and Orrit. Today the principles of detection of a single spin based on ODMR are well established. The limitation of the lateral resolution of ODMR is related to the size of the light spot. The highest resolution is obtained by a near-field scanning optical microscope (NSOM), which has a light spot size of about 30-50 nm. Another limitation of the ODMR technique is that the unpaired electron has to be a part of a molecule, which absorbs or emits light.